High hydrogel SERS platform based on Ag-Au alloy nanoparticles and its application for quantitative analysis of methyl parathion and triazophos

High hydrogel SERS platform based on Ag-Au alloy nanoparticles and its application for quantitative analysis of methyl parathion and triazophos | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article High hydrogel SERS platform based on Ag-Au alloy nanoparticles and its application for quantitative analysis of methyl parathion and triazophos Rongjing Hu, Shilan Fu, Jingwen Zhang, Jiadan Zhang, Fengfu Fu, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9062681/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract A new method is developed to synthesize Au/Ag alloy nanoparticles (Au/Ag-NPs). The obtained Au/Ag-NPs are further dispersed in polyvinyl alcohol (PVA) solution to constructure Au/Ag hydrogel surface enhanced Raman scattering (SERS) chips through a simple Ca 2+ mediated aggregation of Au/Ag-NPs and a physical crosslinking of PVA. The formed aggregated Au/Ag-NPs (a-Au/Ag-NPs) show a strong localized surface plasmon resonance corresponding to the commonly used 532 nm laser. Therefore, under the action of 532 nm laser, the abundant nanogaps contained in the a-Au/Ag-NPs turn to high active electromagnetic “hot spots”, providing strong electromagnetic enhancement (EM). Moreover, Au/Ag-NPs provide a moderate Fermi level of -4.72 eV, which facilitates its photo induced charge transfer with many molecules under 532 nm laser, resulting in the chemical enhancement (CM) effect. The synergistic effect of EM and CM leads to ultrahigh SERS activity. Additionally, the unique structure of hydrogel provides excellent signal uniformity and robust anti-interference ability. Thus, the obtained Au/Ag hydrogel SERS chips are ideal SERS platform for the quantitative analysis of many molecules. For instance, a sensitive and reliable SERS method is established for the simultaneous detection of methyl parathion and triazophos in fruits and tea. Au/Ag alloy Localized surface plasmon resonance Photo-induced charge transfer Surface enhanced Raman scattering Organophosphorus pesticides Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Highlights 1. A facile method synthesizes uniform 18±2 nm Au/Ag alloy nanoparticles (Au/Ag NPs) and assembles them into hydrogel chips with abundant hotspots for strong 532 nm LSPR. 2. The Au/Ag-NPs provide a moderate Fermi level of -4.72 eV, enabling efficient photo-induced charge transfer with target molecules for significant chemical enhancement. 3. A highly sensitive and reliable SERS sensor was established for the simultaneous detection and quantification of methyl parathion and triazophos in complex food matrices. Introduction Since the interesting phenomenon of greatly enhanced Raman signals of pyridine molecules adsorbed on rough silver surfaces was first discovered in 1974 [ 1 ], surface enhanced Raman scattering (SERS) has gradually captured the attention of the scientific community [ 2 ]. Currently, SERS has demonstrated great application potential in various fields such as analytical science [ 3 – 4 ], surface science [ 5 ], and biological science [ 6 – 7 ]. Particularly in the past decade, driven by the growing demand for trace detection, SERS technology has emerged as one of the research hotspots [ 8 ]. For a long time, the application of SERS in quantitative analysis faces significant obstacles [ 9 – 10 ], primarily due to the limitations of existing SERS substrates. Quantitative analysis poses stringent requirements on SERS substrates. Firstly, and most importantly, the SERS signal of the target molecule on the substrate should possess excellent uniformity. Traditional SERS substrates, including both liquid and solid types, generally exhibit poor signal uniformity. This is typically caused by the uneven or unstable distribution of active nanoparticles or the presence of the “coffee ring” effect. Fortunately, recently developed hydrogel SERS chips offer an excellent alternative [ 11 – 14 ]. Hydrogel is a polymer characterized by a three-dimensional network structure formed through the physical or chemical cross-linking of water-soluble or hydrophilic polymers [ 15 ]. Within the three-dimensional hydrogel structure, SERS active materials can achieve a uniform and stable distribution. Furthermore, target molecules can evenly penetrate the hydrogel via diffusion, effectively avoiding the formation of the “coffee ring”. Consequently, hydrogel SERS chips typically demonstrate outstanding signal uniformity, providing significant advantages for quantitative analysis. Secondly, meeting the demands of quantitative analysis also requires the substrate to exhibit sufficient sensitivity towards the target molecule. Based on the established SERS mechanisms, it is essential to balance chemical enhancement (CM) and electromagnetic enhancement (EM) [ 11 , 16 ]. In principle, SERS substrates must possess a strong localized surface plasmon resonance (LSPR) with a wavelength matching that of the excitation laser to achieve a strong EM effect [ 2 , 17 ]. Additionally, they must provide appropriate energy levels for photo-induced charge transfer (PICT) with the target molecule to obtain a strong CM effect [ 18 – 21 ]. Current hydrogel SERS chips universally utilize gold or silver nanostructures, rich in electromagnetic “hot spots”, as the SERS-active materials. These materials inherently exhibit strong EM effects. They also possess Fermi levels, enabling them to form PICT with certain molecules under laser excitation, thereby generating a CM effect. However, the Fermi levels of gold or silver nanostructures are relatively fixed (typically around − 4.5 eV for silver and − 5.1 eV for gold) and difficult to modulate [ 22 , 23 ]. Consequently, with a fixed laser energy, the range of molecules possessing molecular energy levels suitable for forming efficient PICT with the substrate to achieve a strong CM effect is relatively limited. This significantly restricts the application scope of hydrogel SERS chips. Employing Au/Ag alloy nanostructures, rich in electromagnetic “hot spots”, as the SERS-active material could enable the modulation of their Fermi level between − 4.5 eV and − 5.1 eV (depending on the ratio). This modulation would allow more molecules to simultaneously achieve strong EM and CM effects, ultimately greatly expanding the application scope of hydrogel SERS chips. Herein, a facile method for preparing Au/Ag alloy nanoparticles (Au/Ag-NPs) is established. The obtained particles feature an extremely uniform size distribution and can form a stable and homogeneous dispersion in polyvinyl alcohol (PVA) solution. Thus, through the Ca 2+ mediated aggregation of Au/Ag-NPs in PVA and physical cross-linking, hydrogel SERS chips are ultimately constructed [ 11 ]. The hydrogel SERS chip fabricated by this method exhibits a very strong LSPR near 532 nm, enabling it to generate a large number of electromagnetic “hot spots” under the irradiation of a 532 nm laser [ 24 ]. Moreover, the Au/Ag-NPs provide a moderate Fermi level, allowing methyl parathion and triazophos to undergo effective PICT with Au/Ag-NPs under a 532 nm laser, resulting in a strong CM effect. Therefore, the constructed Au/Ag hydrogel SERS chip can produce very sensitive response to methyl parathion and triazophos. On this basis, a sensitive and reliable SERS method was established for the simultaneous detection of two organophosphorus pesticides (OPs), namely methyl parathion and triazophos, in fruits and tea. Experimental Materials and Reagents Silver nitrate (AgNO 3 , 99.8%), chloroauric acid trihydrate (HAuCl 4 ⋅3H 2 O, 99.9%), (+)-D-glucose (99.0%), 4-mercaptobenzoic acid (4-MBA, 99%) were purchased from Macklin (Shanghai, China). Dimethoate, chlorpyrifos (≥ 99%), triazophos (≥ 97%) and methyl parathion (100 µg/ml in acetone) and polyvinyl alcohol (PVA, 1799, alcoholysis degree 98–99%) were purchased from Aladdin (Shanghai, China). Sodium hydroxide (NaOH), and other chemical regents were of analytical grade. Deionized water (DI water, 18.2 MΩ • cm) from a Thermo Scientific Nanopure system was used throughout the experiment. Synthesis of Au/Ag-NPs : Au/Ag-NPs were synthesized via the simultaneous reduction of Ag + and AuCl 4 - with citrate serving as the capping agent. In a typical experimental procedure, 80 mL of DI water was placed into a 200-mL beaker and heated to boiling using a heating plate. Under continuous magnetic stirring, 800 µL of sodium citrate solution (0.1 mol/L), 240 µL of AuCl 4 - solution (0.1 mol/L), and 2.2 mL of NaOH solution (0.1 mol/L) were added sequentially to the beaker. Within 1 minute, the solution underwent a distinct color change: it shifted from light yellow to colorless and then to pink, which was a clear indication of the formation of Au seeds. Subsequently, a pre-prepared mixture consisting of 360 µL of AgNO 3 solution (0.1 mol/L) and 2.4 mL of glucose solution (0.1 mol/L) was promptly added to the reaction system. The solution turned yellow within 1 minute, signifying the successful generation of Au/Ag-NPs. Finally, after allowing the reaction mixture to cool naturally to room temperature, the resulting sol was centrifuged at 12000 rpm for 10 minutes to remove the supernatant. The collected precipitate was then re-dispersed in 2 mL of DI water to obtain a clean Au/Ag-NPs sol with a concentration of 3.80 mg/mL. Preparation of Au/Ag hydrogel SERS chips The Au/Ag hydrogel SERS chips were fabricated based on a slightly modified version of a previously reported method [ 11 ]. Briefly, 30 µL of Ca 2+ solution (0.1 mol/L) and 70 µL of DI water were added to 3 g of 12% PVA solution. The mixture was stirred continuously for 5 minutes to ensure the uniform distribution of the added Ca 2+ ions within the PVA solution. Subsequently, 500 µL of the as-prepared alloy sol was added drop-by-drop under continuous stirring. Within a few minutes, the color of the sol changed from bright yellow to red, which indicated the aggregation of Au/Ag-NPs. After 2 hours of stirring, the stirring was terminated, while the sol was allowed to stand for an additional 30 minutes to remove the air bubbles. Then, the sol was carefully pipetted into 96-well plates, with the height of the sol in each controlled to approximately 0.5 cm. Finally, the sol in the plates underwent 4 freeze-thaw cycles, at -24°C and room temperature, to form the Au/Ag hydrogel SERS chips. SERS detection All the Raman and SERS signal was collected using a portable a Renishaw Invia Raman spectrometer system using a 532 nm laser. In brief, the Au/Ag hydrogel SERS chips were soaked in the standard solutions, blank sample or spiked sample solutions for a demand time. Then, the soaked chips were taken out and put on a slide for the SERS detection. Detection of OPs in real samples All the fruits (apple, grape or oranges) and tea were obtained from a local market in Fuzhou (China). 50 g of the peeled fruit was homogenized. 1.0 g of the homogenized sample was added into a 10 mL centrifuge tube, and was spiked using a standard solution of OPs to obtain the final concentrations of 0 (blank), 1 and 10 ng/mL. Then, 3 g of ethanol was added and vortex-mixed for 1 min. Subsequently, the mixture was ultrasonicated for 10 min, and then centrifuged at 10 000 rpm for 10 min to collect the supernatant for the SERS detection. The processing process of tea samples is similar to that of fruits, except that homogenization treatment is not required. Results and discussion Synthesis of Au/Ag-NPs : The transmission electron microscopy (TEM) image shows the morphologies of the obtained materials (Fig. 1 a). They are mainly spherical nanoparticles with uniform size, approximately 18 ± 2 nm. The size distribution of the materials can be supported by the corresponding DLS spectrum, which exhibits a sharp peak at around 20 nm (Fig. 1 b). The high-resolution TEM (HRTEM) image displays clear and complete lattice fringes with a distance of about 0.23 nm (Fig. 1 c), suggesting the good crystallinity of the nanoparticles. It can also be supported by the X-ray diffraction (XRD) pattern (Fig. 1 d). There are four well-distinguishable diffraction peaks at 38.35, 44.57, 65.02 and 77.68 °, corresponding to the (111), (200), (220) and (311) planes of Au/Ag alloy, respectively (Card PDF#65-8424-Au-Ag). X-ray photoelectron spectroscopy (XPS) spectrum indicates that the obtained nanoparticles should be mainly composed of Ag and Au elements, as well as a certain amount of carbon and oxygen elements (Fig. 1 e). The atomic ratio of Ag to Au is about 5/3, which is consistent with the usage of raw materials. The high resolution XPS spectrum of Au 4f shows two typical peaks of metallic Au at 83.08 and 86.78 eV (Fig. 1 f), assigning to Au 4f7/2 and Au 4f5/2 , respectively [ 25 ]. The high resolution XPS spectrum of Ag 3d exhibits two peaks of metallic Ag at 368.28 and 374.28 eV, attributed to the Ag 3d5/2 and Ag 3d3/2 , respectively [ 26 ]. The high resolution XPS spectrum of C 1s presents the binding energy peaks of C-OH, C = O and COO - groups, suggesting the presence of carboxyl groups on the materials (Fig. S1 ). The carboxyl groups can also be confirmed by the FTIR spectrum (Fig. S2). The results indicate that the obtained nanoparticles should be mainly composed of metallic Ag and Au, while the surface should be modified with a large number of carboxyl groups. The EDX mapping analysis shows uniform distribution of Ag and Au components in the nanoparticles (Fig. 1 g). All the characterization results substantially demonstrate that the obtained spherical nanoparticles are Au/Ag-NPs. The Au/Ag-NPs are strongly negatively charged (Zeta potential: -18.8 mV) due to the surface-modified carboxyl groups, and show excellent dispersity in water (see the inset in Fig. 1 h). The Au/Ag-NP sol displays a typical LSPR absorption band at around 445 nm (Fig. 1 h). The number is between the LSPR wavelengths of monodispersed AgNPs and AuNPs of similar size, which is also a typical feature of Au/Ag-NPs [ 27 ]. Preparation of Au/Ag hydrogel SERS chips To prepare the hydrogel SERS chips, the obtained Au/Ag-NPs were dispersed in 10% PVA solution containing Ca 2+ ions of an appropriate concentration. The Au/Ag-NPs aggregate in the PVA solution due to interaction between the carboxyl groups on the Au/Ag-NPs and Ca 2+ ions [ 11 ]. It can be seen that the yellow sol of Au/Ag-NPs turns to red as being added into the PVA solution (see the inset in Fig. 2 a), suggesting the formation of aggregated Au/Ag-NPs (a-Au/Ag-NPs). The formed a-Au/Ag-NPs exhibit good stability in PVA solution, and even after standing for several hours, there is no sign of precipitation. The a-Au/Ag-NPs produce a sharp LSPR peak at around 532 nm (Fig. 2 a), which matches well with the commonly used laser wavelength of 532 nm in SERS detection. The TEM image indicates that the formed a-Au/Ag-NPs are mainly composed of dozens of Au/Ag-NPs (Fig. 2 b). There are abundant nanogaps in the a-Au/Ag-NPs, which become electromagnetic “hot spots” under the irradiation of 532 nm laser. It should be pointed out that the LSPR peak of the a-Au/Ag-NPs is much sharper and stronger than that produced by the aggregated silver nanoparticles (a-AgNPs) obtained by the similar method [ 11 , 28 ]. It should be related to the better size uniformity of the a-Au/Ag-NPs than the a-AgNPs. Whatever, the obtained a-Au/Ag-NPs should possess quite strong EM effect under the irradiation of 532 nm laser. After the physical crosslinking, Au/Ag hydrogel SERS chips are obtained (Fig. 2 c). It can be observed that the color of a-Au/Ag-NP in PVA solution remains almost unchanged during the physical crosslinking process, suggesting no significant change in the morphology of a-Au/Ag-NPs. Thus, molecules on the obtained Au/Ag hydrogel SERS chips can gain strong EM effect. As long as the target molecule has an appropriate molecular energy level to allow it to undergo PICT with Au/Ag-NPs, strong CM effect can be also received. Therefore, it can be expected that the Au/Ag hydrogel SERS chips have excellent SERS activity to many molecules. 4-MBA is chosen as a model molecule to demonstrate the SERS activity of the Au/Ag hydrogel SERS chips. The Fermi level of Au/Ag-NPs was measured to be ~-4.72 eV (Fig. 2 d), and HOMO and LUMO of 4-MBA are − 8.48 and − 3.21 eV, respectively [ 29 ]. As shown in Fig. 2 e, under the irradiation of 532 nm laser (2.33 eV), PICT from the Fermi level of Au/Ag-NPs to LUMO of 4-MBA is allowed. As expected, the Au/Ag hydrogel SERS chips show excellent SERS activity to 4-MBA. The SERS signal of 4-MBA can be still well distinguished even at a quite concentration of 1×10 –12 mol/L (Fig. 2 f). The enhancement factor (EF) is as high as 1.11×10 11 (see the detailed calculation in the SI). In addition to high SERS activity, the hydrogel SERS chips show outstanding reliability. First of all, the hydrogel SERS chips show excellent signal uniformity. SERS spectra of 4-MBA were collected randomly from 50 points of the chips (Fig. 2 g). All the spectra are highly consistent. The relative standard deviation (RSD) based on the peak intensity at 1071 cm -1 in the 50 spectra is as low as 3.5%. Secondly, the SERS activity of the Au/Ag hydrogel SERS chips show good long-term stability. The peak intensity of 4-MBA at 1537 cm -1 on the chip remains above 94% after three-month storage in refrigerator (Fig. S3). SERS response to OPs The experimental results mentioned above suggest that the obtained Au/Ag hydrogel SERS chips have excellent activity, uniformity and stability, and thereby should be an ideal SERS platform for quantitative detection. To further confirm the reliability, the SERS platform was applied for the detection of OPs. Figure 3 a-d show the molecular energy levels of four common OPs, namely dimethoate, chlorpyrifos, methyl parathion, and triazophos, as well as the PICT processes between the OPs and Au/Ag-NPs under the irradiation of 532 nm laser. HOMO and LUMO of dimethoate are − 9.07 and − 0.84 eV, respectively [ 30 ]. Both of them are far from the Fermi level of Au/Ag-NPs, and the PICT cannot be activated by the 532 nm laser (Fig. 3 a). Consequently, the CM effect induced by PICT cannot be obtained. What’s worse, the poor conjugation of the molecules leads to small Raman cross section 2 . As a result, even though the obtained Au/Ag hydrogel SERS chip provides rich and strong electromagnetic “hot spots”, dimethoate shows nearly no any distinguishable SERS signal even at a high concentration of 10 µg/mL (Fig. 3 b). Chlorpyrifos and methyl parathion have similar conjugation units, suggesting similar EM effect from the substrate. However, their CM effects are different. HOMO and LUMO of chlorpyrifos are − 8.37 and − 3.01 eV, respectively [ 31 ]. PICT from the Fermi level of Au/Ag-NPs to the LUMO can be activated by the laser, producing CM effect. However, the laser energy is much bigger than the energy interval. The mismatched laser energy may limit the PICT efficiency, and inhibit the CM effect (Fig. 3 c). As a result, the SERS response of the hydrogel SERS chip to the molecule is not quite sensitive (Fig. 3 d). HOMO and LUMO of methyl parathion are − 6.97 and − 2.40 eV, respectively [ 32 ]. The 532 nm laser can well activate simultaneously the PICT process from the HOMO of molecule to the Fermi level of Au/Ag-NPs and that from the Fermi level of Au/Ag-NPs to LUMO of molecule (Fig. 3 e). Therefore, methyl parathion can also gain strong CM effect, and shows strong signal on the hydrogel SERS chip (Fig. 3 f). HOMO and LUMO of triazophos are calculated to ~-6.66 and − 1.42 eV, respectively (Table S1 , Fig. S4). Similar to the case of chlorpyrifos, the laser energy does not closely match the energy gap involved in the PICT process for triazophos, which should also limit its CM effect to some extent (Fig. 3 g). However, triazophos possesses a larger conjugated structure compared to chlorpyrifos, enabling it to achieve a stronger EM enhancement. Consequently, the SERS signal of triazophos on the obtained Au/Ag hydrogel SERS chip is also significantly stronger than that of chlorpyrifos (Fig. 3 h). As presented in the above experimental results, the constructed Au/Ag hydrogel SERS chips are sensitive only to the OPs, which have big Raman cross section and propriate molecular energy levels meeting the necessary for the PICT with the Au/Ag-NPs, but are insensitive to other OPs. That is to say, the SERS response of the developed Au/Ag hydrogel SERS chips to triazophos and methyl parathion can largely resist the interference of other OPs, which is quite important for the selective detection. Developing SERS sensor for triazophos and methyl parathion The hydrogel SERS chips are sensitive to both triazophos and methyl parathion, and the measured SERS spectra of the two OPs are quite different. Thus, SERS sensors can be developed simultaneously for the detection of triazophos and methyl parathion. First of all, the effect of the solvent on the SERS response to the two OPs was investigated. Apparently, the solvent greatly affects not only the SERS spectra of the two OPs, but also the intensity of their main peaks (Fig. 4 a, b). It may be because the solvent not only affects the efficiency of OPs molecules passing through the hydrogel pores, but also affects the interaction sites of OPs molecules on Au/Ag-NPs in the hydrogel. It can be seen that ethanol suits for both the two OPs, and would be applied in the following detection. Secondly, the soaking time will affect the enrichment of OP molecules in the Au/Ag hydrogel SERS chips, and should be optimized. It can be clearly observed that as the soaking time increases, the SERS intensity of the two OPs first increases and then tends to stabilize (Fig. 4 c, d). Both the strongest characteristic peaks of methyl parathion at 1345 cm -1 and triazophos at 1595 cm -1 increase sharply with the soaking time in the first 25 min, but increase slightly with further soaking time (Fig. 4 e, f). For rapid detection technology, short response time and high sensitivity are equally important. Therefore, the soaking time for the detection of the two OPs is selected as 25 min. Under the optimized experimental conditions mentioned above, the constructed Au/Ag hydrogel SERS chips exhibit ideal SERS response to the two OPs. Figure 5 a, b shows the SERS spectra of methyl parathion and triazophos at various concentrations, respectively. It can be clearly seen that the main characteristic SERS peaks of methyl parathion can still be distinguished even at an extremely low concentration of 0.01 ng/mL, and the SERS peaks of triazophos can also be recognized at a low concentration of 0.1 ng/mL. Apparently, the values are much lower than the maximum residue limits set internationally for the two OPs [ 33 ]. Actually, the sensitivities are better than those of most reported rapid detection methods for the two OPs (Table S2-S3). It can also be observed from the fiugres, the SERS signals of the two OPs increase gradually as the concentration increases. The intensity of the strongest characteristic peak of methyl parathion at 1345 cm -1 shows a good linear relationship with the logarithm of its concentration over a wide range of 0.01 to 1000 ng/mL, (Fig. 5 c). Similarly, the peak intensity of triazophos at 1595 cm -1 also shows a good semi-logarithmic relationship with the concentration from 0.1 to 1000 ng/mL (Fig. 5 d). The results suggest that the constructed Au/Ag hydrogel SERS chips can act as a sensitive SERS platform for the quantitative analysis of the two OPs. Except for the high sensitivity, the unique structure of hydrogels should endow the hydrogel SERS chips excellent anti-interference ability. Therefore, it can be expected that the constructed Au/Ag hydrogel SERS chips should exhibit outstanding practicability in the application of real samples. To check it, four real samples including apple, grape, orange and tea are used. Although the samples exhibit some background signals, they do not present any characteristic peaks of methyl parathion or triazophos (Fig. S5). The concentrations of methyl parathion and triazophos in the samples should be lower than the detection limits of the SERS platform, and can be ignored. Therefore, all the samples were spiked with 1 and 10 ng/mL methyl parathion or triazophos. It can be seen that all the spiked samples produce well distinguishable SERS signals of methyl parathion or triazophos (Fig. S6, S7), and the background signals from the samples are greatly inhibited. The recoveries of methyl parathion in the samples are in the range of 77.58 ~ 109.50%, and those of triazophos are in the range of 78.17 ~ 103.31% (Table 1 ). The acceptable results substantially confirm the reliability of the SERS platform for the detection of methyl parathion and triazophos in real samples. Table 1 Recovery tests for methyl parathion and triazophos using the designed SERS sensor. Samples Methyl parathion Triazophos Spiked (ng/mL) Detected (ng/mL) Recovery (%) Spiked (ng/mL) Detected (ng/mL) Recovery (%) Apple 1.00 0.81 80.79 1.00 0.92 92.04 10.00 8.04 80.39 10.00 9.44 94.43 Grape 1.00 0.78 77.58 1.00 0.78 78.17 10.00 8.61 86.07 10.00 8.51 85.13 Orange 1.00 0.89 89.06 1.00 1.03 103.31 10.00 10.12 101.83 10.00 8.50 84.98 Tea 1.00 0.88 88.51 1.00 0.92 91.76 10.00 10.95 109.50 10.00 8.89 89.94 Conclusion Au/Ag-NPs with a uniform diameter distribution of 18 ± 2 nm have been synthesized and applied to construct hydrogel SERS chips. The formed a-Au/Ag-NPs in the hydrogel on one hand provide lots of electromagnetic “hot spots” to produce strong EM effect, and on the other hand provide a moderate Fermi level at -4.72 eV for the PICT with many molecules to gain strong CM effect. Meanwhile, the construction of hydrogel substrates significantly enhanced the homogeneity and stability of a-Au/Ag-NPs. The constructed Au/Ag hydrogel SERS chips have been proved to be a sensitive and reliable sensing platform for the detection of methyl parathion and triazophos in fruit and tea samples and also quantitative analysis of molecules having appropriate molecular energy levels for the PICT with the Au/Ag-NPs. Declarations Author contribution Rongjing Hu: Data curation, Investigation, Methodology, Validation, Visualization, Writing – original draft. Shilan Fu: Investigation, Methodology, Validation, Writing – original draft. Jingwen Zhang: Investigation, Methodology, Formal analysis. Jiadan Zhang: Conceptualization, Data curation, Validation. Fengfu Fu: Conceptualization, Funding acquisition, Project administration, Resources. Zhenyu Lin: Conceptualization, Funding acquisition, Project administration, Resources. Yongqiang Dong: Conceptualization, Funding acquisition, Project administration, Resources, Supervision, Writing – review and editing. Funding This study was financially supported by the National Key R&D Program of China (2023YFF1105300), the National Natural Science Foundation of China (22276032), the Natural Science Foundation of Fujian Province (2023N0030, 2022Y0059, 2022J01537). Data availability No datasets were generated or analysed during the current study. Conflict of interest The authors declare no competing interests. Supplementary Information The online version contains supplementary material available at https:// doi. org/ Data Availability Data will be made available on request. References Fleischmann M, Hendra PJ, McQuillan AJ (1974) Raman spectra of pyridine adsorbed at a silver electrode. Chem Phys Lett 26(2):163–166. https://doi.org/10.1016/0009-2614(74)85388-1 Wang X, Huang SC, Hu S et al (2020) Fundamental understanding and applications of plasmon-enhanced Raman spectroscopy. Nat Rev Phys 2(5):253–271. https://doi.org/10.1038/s42254-020-0171-y Bell SEJ, Charron G, Cortés E et al (2020) Towards reliable and quantitative surface-enhanced Raman scattering (SERS): from key parameters to good analytical practice. Angew Chem Int Ed 59(14):5454–5462. https://doi.org/10.1002/anie.201908154 Dai Q, Huang J, Qiu X et al (2025) A chiral sensing system based on a single Au nanowire: a general SERS strategy for identification of enantiomers and mechanism for chiral interaction. Anal Chem 97(6):3765–3772. https://doi.org/10.1021/acs.analchem.5c00036 Huang XX, Wang HJ, Yang JL et al (2023) Direct S–H evidence revealing the photo-electrocatalytic hydrogen evolution reaction mechanism on CdS using surface-enhanced Raman spectroscopy. J Phys Chem Lett 14(17):4026–4032. https://doi.org/10.1021/acs.jpclett.3c00701 Lin L, He H, Xue R et al (2023) Direct and quantitative assessments of near-infrared light attenuation and spectroscopic detection depth in biological tissues using surface-enhanced Raman scattering. Med-X 1(1):2–17. https://doi.org/10.1007/s44258-023-00010-2 Song L, Xue F, Li TM et al (2025) Differential diagnosis of urinary cancers by surface-enhanced Raman spectroscopy and machine learning. Anal Chem 97(1):11939–11941. https://doi.org/10.1021/acs.analchem.4c05287 Rycenga M, Cobley CM, Zeng J et al (2011) Controlling the synthesis and assembly of silver nanostructures for plasmonic applications. Chem Rev 111(6):3669–3712. https://doi.org/10.1021/cr100275d Zhang L, Su LZ, Yu Z et al (2022) Quantitative detection of creatinine in human serum by SERS with evaporation-induced optimal hotspots on Au nanocubes. ACS Appl Nano Mater 5(4):4841–4847. https://doi.org/10.1021/acsanm.1c04421 Xu J, Xie LF, Zhu MJ et al (2024) Rapid sample pretreatment facilitating SERS detection of trace weak organic acids/bases in simple matrices. Anal Chem 96(15):5968–5975. https://doi.org/10.1021/acs.analchem.4c00229 Chen M, Liu Z, Su B et al (2023) High-performance hydrogel SERS chips with tunable localized surface plasmon resonance for coordinated electromagnetic enhancement with chemical enhancement. Adv Opt Mater 11(7):2202852. https://doi.org/10.1002/adom.202202852 Chen M, Zhang J, Zhu X et al (2022) Hybridizing silver nanoparticles in hydrogel for high-performance flexible SERS chips. ACS Appl Mater Interfaces 14(22):26216–26224. https://doi.org/10.1021/acsami.2c04628 Li G, Zhao X, Tang X et al (2024) Wearable hydrogel SERS chip utilizing plasmonic trimers for uric acid analysis in sweat. Nano Lett 24(42):13447–13454. https://doi.org/10.1021/acs.nanolett.4c04267 Chen Y, Zhang Z, Wu Y et al (2025) Utilizing hydrogel-isolated dual-carboxyl surface-enhanced Raman scattering probe for accurate online pH monitoring. ACS Sens 10(11):8975–8982. https://doi.org/10.1021/acssensors.5c03124 Xiao Z, Li Q, Liu H et al (2022) Adhesion mechanism and application progress of hydrogels. Eur Polym J 173:111277. https://doi.org/10.1016/j.eurpolymj.2022.111277 Serafinelli C, Fantoni A, Alegria ECBA et al (2022) Plasmonic metal nanoparticles hybridized with 2D nanomaterials for SERS detection: a review. Biosensors 12(4):225. https://doi.org/10.3390/bios12040225 Song J, Nam W, Zhou W (2019) Scalable high-performance nanolaminated SERS substrates based on multistack vertically oriented plasmonic nanogaps. Adv Mater Technol 4(5):2202345. https://doi.org/10.1002/admt.201800689 Fu X, Wu H, Liu Z et al (2024) MoS 2 nanosheets as substrates for SERS-based sensing. ACS Appl Nano Mater 7:3988–3996. https://doi.org/10.1021/acsanm.3c05606 Lin J, Shang Y, Li X et al (2017) Ultrasensitive SERS detection by defect engineering on single Cu 2 O superstructure particle. Adv Mater 29(5):1604797. https://doi.org/10.1002/adma.201604797 Xu W, Gong X, Xiao J et al (2012) Surface-enhanced Raman spectroscopy on flat graphene surface. Proc Natl Acad Sci USA 109(23):9281–9286. https://doi.org/10.1073/pnas.1205478109 Chaudhry I, Hu G, Ye H et al (2024) Toward modeling the complexity of the chemical mechanism in SERS. ACS Nano 18(32):20835–20850. https://doi.org/10.1021/acsnano.4c07198 Wang P, Tanaka D, Ryuzaki S et al (2015) Silver nanoparticles with tunable work functions. Appl Phys Lett 107(15):151601. https://doi.org/10.1063/1.4933253 Musa I, Ghabboun J (2025) Work function, electrostatic force microscopy, tunable photoluminescence of gold nanoparticles, and plasmonic interaction of gold nanoparticles/rhodamine 6G nanocomposite. Plasmonics 20:2531–2540. https://doi.org/10.1007/s11468-024-02484-1 Fang Y, Seong NH, Dlott DD (2008) Measurement of the distribution of site enhancements in surface-enhanced Raman scattering. Science 321(5887):388–392. https://doi.org/10.1126/science.1159499 Luo P, Li C, Shi G (2012) Synthesis of gold@carbon dots composite nanoparticles for surface enhanced Raman scattering. Phys Chem Chem Phys 14(20):7360–7366. https://doi.org/10.1039/c2cp40767a Yang L, Jiang X, Ruan W et al (2009) Charge-transfer-induced surface-enhanced Raman scattering on Ag-TiO₂ nanocomposites. J Phys Chem C 113(36):16226–16231. https://doi.org/10.1021/jp903600r Qiu G, Ng SP, Wu CML (2018) Bimetallic Au-Ag alloy nanoislands for highly sensitive localized surface plasmon resonance biosensing. Sens Actuators B 265:459–467. https://doi.org/10.1016/j.snb.2018.03.066 Chen M, Su B, Wu H et al (2024) Hydrogel SERS chip with strong localized surface plasmon resonance for sensitive and rapid detection of T-2 toxin. Talanta 268:125329. https://doi.org/10.1016/j.talanta.2023.125329 Yang N, Guo NS, Park E et al (2024) Surface plasmon resonance-induced charge transfer in Ag/mercaptobenzoic acid/polyaniline sandwich structures. J Phys Chem C 128(9):3876–3884. https://doi.org/10.1021/acs.jpcc.4c00292 Souza IC, Goncalves AS et al (2019) Computational studies of fullerene derivatives as pesticide captors. Orbital Electron J Chem 11(1):10–17. http://dx.doi.org/10.17807/orbital.v11i1.1215 Suresh I, Nesakumar N, Jegadeesan GB et al (2023) Quantification of chlorpyrifos residues in water under thermodynamically favorable electrodics using the f-MWCNT/N-(2-C 2 H 5 O)ED(CH 3 COONa) 3 composite of superior selectivity. J Agric Food Chem 71(20):7642–7653. https://doi.org/10.1021/acs.jafc.3c00123 He K, Li Z, Wang L et al (2019) A water-stable luminescent metal–organic framework for rapid and visible sensing of organophosphorus pesticides. ACS Appl Mater Interfaces 11(29):26250–26260. https://doi.org/10.1021/acsami.9b06151 Yang FW, Li YX, Ren FZ et al (2019) Toxicity, residue, degradation and detection methods of the insecticide triazophos. Environ Chem Lett 17:1769–1785. https://doi.org/10.1007/s10311-019-00910-z Additional Declarations No competing interests reported. Supplementary Files SI.docx floatimage1.jpeg Graphical Abstract The hydrogel-embedded uniform Au/Ag nanoparticles function as a dual-enhanced SERS platform, utilizing both electromagnetic hotspots and favorable charge transfer for sensitive pesticide detection in food samples. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 15 Apr, 2026 Reviews received at journal 11 Apr, 2026 Reviewers agreed at journal 29 Mar, 2026 Reviews received at journal 20 Mar, 2026 Reviewers agreed at journal 15 Mar, 2026 Reviewers invited by journal 13 Mar, 2026 Editor assigned by journal 10 Mar, 2026 Submission checks completed at journal 09 Mar, 2026 First submitted to journal 08 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9062681","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":606393605,"identity":"aff170f8-20ac-40da-8915-0c1dad576c2b","order_by":0,"name":"Rongjing Hu","email":"","orcid":"","institution":"Fuzhou University","correspondingAuthor":false,"prefix":"","firstName":"Rongjing","middleName":"","lastName":"Hu","suffix":""},{"id":606393608,"identity":"89463e33-2256-4e59-ba6c-09cb8b3b7225","order_by":1,"name":"Shilan Fu","email":"","orcid":"","institution":"Shanghai Jiao Tong University","correspondingAuthor":false,"prefix":"","firstName":"Shilan","middleName":"","lastName":"Fu","suffix":""},{"id":606393610,"identity":"3c579ccc-c892-48d5-9e92-c0ca4dc42da8","order_by":2,"name":"Jingwen Zhang","email":"","orcid":"","institution":"Fuzhou University","correspondingAuthor":false,"prefix":"","firstName":"Jingwen","middleName":"","lastName":"Zhang","suffix":""},{"id":606393613,"identity":"414fae7f-3cb7-4419-80fd-3050805eeaaa","order_by":3,"name":"Jiadan Zhang","email":"","orcid":"","institution":"Fuzhou University","correspondingAuthor":false,"prefix":"","firstName":"Jiadan","middleName":"","lastName":"Zhang","suffix":""},{"id":606393616,"identity":"4b9613e9-d5c8-4fa2-8b1c-c36f1149a6df","order_by":4,"name":"Fengfu Fu","email":"","orcid":"","institution":"Fuzhou University","correspondingAuthor":false,"prefix":"","firstName":"Fengfu","middleName":"","lastName":"Fu","suffix":""},{"id":606393619,"identity":"66c99fa0-a4a8-4aa9-8e5f-f7f71ff35f23","order_by":5,"name":"Zhenyu Lin","email":"","orcid":"","institution":"Fuzhou University","correspondingAuthor":false,"prefix":"","firstName":"Zhenyu","middleName":"","lastName":"Lin","suffix":""},{"id":606393622,"identity":"3542f5e1-a975-4015-ab8f-9356c7b827f2","order_by":6,"name":"Yongqiang Dong","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxUlEQVRIiWNgGAWjYDCCA2DShh9M8ZCgJU2ygVQth0nQwne89/BrnrLzEvIzEhgfvG1jkDcnpEXyzLk0a55ztyUYZyQwG85tYzDc2UBAi8GNHDNj3rbbdcwSCWzSvG0MCQYHiNNyToJNIoH9N7FajB/zth2Q4AHawkyUFskzZ8wY55xLlpDgedgsOeechOEGQlr4jvcYf3hTZich3558EMiwkSdoCxCwSfGwgWjGBiAhQVg9EDB//MFGlMJRMApGwSgYqQAAPGs9dxqbXlkAAAAASUVORK5CYII=","orcid":"","institution":"Fuzhou University","correspondingAuthor":true,"prefix":"","firstName":"Yongqiang","middleName":"","lastName":"Dong","suffix":""}],"badges":[],"createdAt":"2026-03-08 07:53:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9062681/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9062681/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104756289,"identity":"4ef1082f-f1f5-4acd-89fb-de27bd61f5fa","added_by":"auto","created_at":"2026-03-16 22:29:05","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1275219,"visible":true,"origin":"","legend":"\u003cp\u003eTEM image (a), DLS spectrum (b), HRTEM image (c), XRD pattern (d) and XPS spectrum (e) of the obtained Au/Ag-NPs, high resolution XPS spectrum of Au\u003csub\u003e4f\u003c/sub\u003e and Ag\u003csub\u003e3d\u003c/sub\u003e of the obtained Au/Ag-NPs (f), EDX elemental maps of Ag and Au and superposition of Ag and Au (g), and UV-vis spectrum of the obtained Au/Ag-NPs, the inset shows the photograph of the obtained Au/Ag-NPs under sunlight (h).\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9062681/v1/a5f6a44d02602a8ec6326d8d.jpg"},{"id":104756295,"identity":"543dff14-ae12-4aa2-8fa0-c04bcb17821f","added_by":"auto","created_at":"2026-03-16 22:29:05","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":5852042,"visible":true,"origin":"","legend":"\u003cp\u003eUV-vis spectrum of a-Au/Ag-NPs in the PVA solution, the inset shows the photograph of the a-Au/Ag-NPs solution under the sunlight (a), TEM images of the a-Au/Ag-NPs (b), photograph of the obtained Au/Ag hydrogel SERS chips under the sunlight (c), UPS spectrum of Au/Ag-NPs (d), Schematic of energy band gap matching between Au/Ag-NPs and 4-MBA (e), Raman spectrum of bulk 4-MBA and SERS spectrum of 4-MBA (1.0 × 10\u003csup\u003e-12\u003c/sup\u003e mol/L) on the hydrogel SERS chip (f), SERS spectra of 4-MBA (1.0 × 10\u003csup\u003e-10\u003c/sup\u003e mol/L) collected from 50 randomly selected points on the hydrogel SERS chip (g).\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9062681/v1/a7c3bb94e020ee74e135dc70.jpg"},{"id":104783391,"identity":"2be91b0d-7c6d-4ce4-a396-fadf3d43e1f2","added_by":"auto","created_at":"2026-03-17 07:58:49","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2001806,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagram illustrating of possible PICT processes between Au/Ag-NPsand probe molecules (a, c, e, g), and the corresponding SERS spectra (b, d, f, h): dimethoate (a, b), chlorpyrifos (c, d), methyl parathion (e, f) and triazophos (g, h). The insets show the structural formulas of corresponding OPs.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9062681/v1/1467e7f284e958d4c06e17ea.jpg"},{"id":104783420,"identity":"f4c5d680-ca60-4a35-a9df-9ceffddc1773","added_by":"auto","created_at":"2026-03-17 07:58:54","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":353963,"visible":true,"origin":"","legend":"\u003cp\u003eResponses of the constructed Au/Ag hydrogel SERS chips to 10 ng/mL methyl parathion (a) and 10 ng/mL triazophos (b) in different solvents. SERS spectra collected on the hydrogel SERS chip after being soaked in 10 ng/mL methyl parathion (c) and 10 ng/mL triazophos (d) for different times. Effect of soaking time on the SERS intensity of methyl parathion at 1345 cm\u003csup\u003e−1\u003c/sup\u003e (e) and the intensity of triazophos at 1595 cm\u003csup\u003e−1\u003c/sup\u003e (f).\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9062681/v1/855720e3309f80bd0597d121.jpg"},{"id":104756294,"identity":"cb004173-bb57-4977-aae9-e64d805ca919","added_by":"auto","created_at":"2026-03-16 22:29:05","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1551888,"visible":true,"origin":"","legend":"\u003cp\u003eSERS spectra of methyl parathion (a) and triazophos (b) of different concentrations on the hydrogel SERS chips. The linear relationship between the peak intensity at 1345 cm\u003csup\u003e−1\u003c/sup\u003e and logarithmic concentration of methyl parathion (c), the linear relationship between the peak intensity at 1595 cm\u003csup\u003e-1\u003c/sup\u003e and the logarithmic concentration of triazophos (d).\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9062681/v1/9a89f31d48ca76552987c2df.jpg"},{"id":104785071,"identity":"a9541016-2342-4848-991e-1e96fb017add","added_by":"auto","created_at":"2026-03-17 08:09:28","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":11659897,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9062681/v1/ea4f78e3-38fe-41f6-b4e6-a025c74c319d.pdf"},{"id":104756291,"identity":"2a9af167-8a77-4046-a012-34024b578ee6","added_by":"auto","created_at":"2026-03-16 22:29:05","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1501428,"visible":true,"origin":"","legend":"","description":"","filename":"SI.docx","url":"https://assets-eu.researchsquare.com/files/rs-9062681/v1/885c4dbbcf58fb8edab2928e.docx"},{"id":104783023,"identity":"65eb5a2a-6763-44ff-b676-69b98bcba5a0","added_by":"auto","created_at":"2026-03-17 07:58:06","extension":"jpeg","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":176585,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGraphical Abstract\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe hydrogel-embedded uniform Au/Ag nanoparticles function as a dual-enhanced SERS platform, utilizing both electromagnetic hotspots and favorable charge transfer for sensitive pesticide detection in food samples.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-9062681/v1/205c1835d5ecc1f82d3ffafc.jpeg"}],"financialInterests":"No competing interests reported.","formattedTitle":"High hydrogel SERS platform based on Ag-Au alloy nanoparticles and its application for quantitative analysis of methyl parathion and triazophos","fulltext":[{"header":"Highlights","content":"\u003cp\u003e1. A facile method synthesizes uniform 18\u0026plusmn;2 nm Au/Ag alloy nanoparticles (Au/Ag NPs) and assembles them into hydrogel chips with abundant hotspots for strong 532 nm LSPR.\u003c/p\u003e\n\u003cp\u003e2. The Au/Ag-NPs provide a moderate Fermi level of -4.72 eV, enabling efficient photo-induced charge transfer with target molecules for significant chemical enhancement.\u003c/p\u003e\n\u003cp\u003e3. A highly sensitive and reliable SERS sensor was established for the simultaneous detection and quantification of methyl parathion and triazophos in complex food matrices.\u003c/p\u003e"},{"header":"Introduction","content":"\u003cp\u003eSince the interesting phenomenon of greatly enhanced Raman signals of pyridine molecules adsorbed on rough silver surfaces was first discovered in 1974 [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], surface enhanced Raman scattering (SERS) has gradually captured the attention of the scientific community [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Currently, SERS has demonstrated great application potential in various fields such as analytical science [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], surface science [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], and biological science [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Particularly in the past decade, driven by the growing demand for trace detection, SERS technology has emerged as one of the research hotspots [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFor a long time, the application of SERS in quantitative analysis faces significant obstacles [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], primarily due to the limitations of existing SERS substrates. Quantitative analysis poses stringent requirements on SERS substrates. Firstly, and most importantly, the SERS signal of the target molecule on the substrate should possess excellent uniformity. Traditional SERS substrates, including both liquid and solid types, generally exhibit poor signal uniformity. This is typically caused by the uneven or unstable distribution of active nanoparticles or the presence of the \u0026ldquo;coffee ring\u0026rdquo; effect. Fortunately, recently developed hydrogel SERS chips offer an excellent alternative [\u003cspan additionalcitationids=\"CR12 CR13\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Hydrogel is a polymer characterized by a three-dimensional network structure formed through the physical or chemical cross-linking of water-soluble or hydrophilic polymers [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Within the three-dimensional hydrogel structure, SERS active materials can achieve a uniform and stable distribution. Furthermore, target molecules can evenly penetrate the hydrogel via diffusion, effectively avoiding the formation of the \u0026ldquo;coffee ring\u0026rdquo;. Consequently, hydrogel SERS chips typically demonstrate outstanding signal uniformity, providing significant advantages for quantitative analysis. Secondly, meeting the demands of quantitative analysis also requires the substrate to exhibit sufficient sensitivity towards the target molecule. Based on the established SERS mechanisms, it is essential to balance chemical enhancement (CM) and electromagnetic enhancement (EM) [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In principle, SERS substrates must possess a strong localized surface plasmon resonance (LSPR) with a wavelength matching that of the excitation laser to achieve a strong EM effect [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Additionally, they must provide appropriate energy levels for photo-induced charge transfer (PICT) with the target molecule to obtain a strong CM effect [\u003cspan additionalcitationids=\"CR19 CR20\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Current hydrogel SERS chips universally utilize gold or silver nanostructures, rich in electromagnetic \u0026ldquo;hot spots\u0026rdquo;, as the SERS-active materials. These materials inherently exhibit strong EM effects. They also possess Fermi levels, enabling them to form PICT with certain molecules under laser excitation, thereby generating a CM effect. However, the Fermi levels of gold or silver nanostructures are relatively fixed (typically around \u0026minus;\u0026thinsp;4.5 eV for silver and \u0026minus;\u0026thinsp;5.1 eV for gold) and difficult to modulate [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Consequently, with a fixed laser energy, the range of molecules possessing molecular energy levels suitable for forming efficient PICT with the substrate to achieve a strong CM effect is relatively limited. This significantly restricts the application scope of hydrogel SERS chips. Employing Au/Ag alloy nanostructures, rich in electromagnetic \u0026ldquo;hot spots\u0026rdquo;, as the SERS-active material could enable the modulation of their Fermi level between \u0026minus;\u0026thinsp;4.5 eV and \u0026minus;\u0026thinsp;5.1 eV (depending on the ratio). This modulation would allow more molecules to simultaneously achieve strong EM and CM effects, ultimately greatly expanding the application scope of hydrogel SERS chips.\u003c/p\u003e \u003cp\u003eHerein, a facile method for preparing Au/Ag alloy nanoparticles (Au/Ag-NPs) is established. The obtained particles feature an extremely uniform size distribution and can form a stable and homogeneous dispersion in polyvinyl alcohol (PVA) solution. Thus, through the Ca\u003csup\u003e2+\u003c/sup\u003e mediated aggregation of Au/Ag-NPs in PVA and physical cross-linking, hydrogel SERS chips are ultimately constructed [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The hydrogel SERS chip fabricated by this method exhibits a very strong LSPR near 532 nm, enabling it to generate a large number of electromagnetic \u0026ldquo;hot spots\u0026rdquo; under the irradiation of a 532 nm laser [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Moreover, the Au/Ag-NPs provide a moderate Fermi level, allowing methyl parathion and triazophos to undergo effective PICT with Au/Ag-NPs under a 532 nm laser, resulting in a strong CM effect. Therefore, the constructed Au/Ag hydrogel SERS chip can produce very sensitive response to methyl parathion and triazophos. On this basis, a sensitive and reliable SERS method was established for the simultaneous detection of two organophosphorus pesticides (OPs), namely methyl parathion and triazophos, in fruits and tea.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cp\u003e \u003cstrong\u003eMaterials and Reagents\u003c/strong\u003e \u003cp\u003eSilver nitrate (AgNO\u003csub\u003e3\u003c/sub\u003e, 99.8%), chloroauric acid trihydrate (HAuCl\u003csub\u003e4\u003c/sub\u003e\u0026sdot;3H\u003csub\u003e2\u003c/sub\u003eO, 99.9%), (+)-D-glucose (99.0%), 4-mercaptobenzoic acid (4-MBA, 99%) were purchased from Macklin (Shanghai, China). Dimethoate, chlorpyrifos (\u0026ge;\u0026thinsp;99%), triazophos (\u0026ge;\u0026thinsp;97%) and methyl parathion (100 \u0026micro;g/ml in acetone) and polyvinyl alcohol (PVA, 1799, alcoholysis degree 98\u0026ndash;99%) were purchased from Aladdin (Shanghai, China). Sodium hydroxide (NaOH), and other chemical regents were of analytical grade. Deionized water (DI water, 18.2 MΩ \u0026bull; cm) from a Thermo Scientific Nanopure system was used throughout the experiment.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of Au/Ag-NPs\u003c/b\u003e: Au/Ag-NPs were synthesized via the simultaneous reduction of Ag\u003csup\u003e+\u003c/sup\u003e and AuCl\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e with citrate serving as the capping agent. In a typical experimental procedure, 80 mL of DI water was placed into a 200-mL beaker and heated to boiling using a heating plate. Under continuous magnetic stirring, 800 \u0026micro;L of sodium citrate solution (0.1 mol/L), 240 \u0026micro;L of AuCl\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e solution (0.1 mol/L), and 2.2 mL of NaOH solution (0.1 mol/L) were added sequentially to the beaker. Within 1 minute, the solution underwent a distinct color change: it shifted from light yellow to colorless and then to pink, which was a clear indication of the formation of Au seeds. Subsequently, a pre-prepared mixture consisting of 360 \u0026micro;L of AgNO\u003csub\u003e3\u003c/sub\u003e solution (0.1 mol/L) and 2.4 mL of glucose solution (0.1 mol/L) was promptly added to the reaction system. The solution turned yellow within 1 minute, signifying the successful generation of Au/Ag-NPs. Finally, after allowing the reaction mixture to cool naturally to room temperature, the resulting sol was centrifuged at 12000 rpm for 10 minutes to remove the supernatant. The collected precipitate was then re-dispersed in 2 mL of DI water to obtain a clean Au/Ag-NPs sol with a concentration of 3.80 mg/mL.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003ePreparation of Au/Ag hydrogel SERS chips\u003c/strong\u003e \u003cp\u003eThe Au/Ag hydrogel SERS chips were fabricated based on a slightly modified version of a previously reported method [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Briefly, 30 \u0026micro;L of Ca\u003csup\u003e2+\u003c/sup\u003e solution (0.1 mol/L) and 70 \u0026micro;L of DI water were added to 3 g of 12% PVA solution. The mixture was stirred continuously for 5 minutes to ensure the uniform distribution of the added Ca\u003csup\u003e2+\u003c/sup\u003e ions within the PVA solution. Subsequently, 500 \u0026micro;L of the as-prepared alloy sol was added drop-by-drop under continuous stirring. Within a few minutes, the color of the sol changed from bright yellow to red, which indicated the aggregation of Au/Ag-NPs. After 2 hours of stirring, the stirring was terminated, while the sol was allowed to stand for an additional 30 minutes to remove the air bubbles. Then, the sol was carefully pipetted into 96-well plates, with the height of the sol in each controlled to approximately 0.5 cm. Finally, the sol in the plates underwent 4 freeze-thaw cycles, at -24\u0026deg;C and room temperature, to form the Au/Ag hydrogel SERS chips.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSERS detection\u003c/strong\u003e \u003cp\u003eAll the Raman and SERS signal was collected using a portable a Renishaw Invia Raman spectrometer system using a 532 nm laser. In brief, the Au/Ag hydrogel SERS chips were soaked in the standard solutions, blank sample or spiked sample solutions for a demand time. Then, the soaked chips were taken out and put on a slide for the SERS detection.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eDetection of OPs in real samples\u003c/strong\u003e \u003cp\u003eAll the fruits (apple, grape or oranges) and tea were obtained from a local market in Fuzhou (China). 50 g of the peeled fruit was homogenized. 1.0 g of the homogenized sample was added into a 10 mL centrifuge tube, and was spiked using a standard solution of OPs to obtain the final concentrations of 0 (blank), 1 and 10 ng/mL. Then, 3 g of ethanol was added and vortex-mixed for 1 min. Subsequently, the mixture was ultrasonicated for 10 min, and then centrifuged at 10 000 rpm for 10 min to collect the supernatant for the SERS detection. The processing process of tea samples is similar to that of fruits, except that homogenization treatment is not required.\u003c/p\u003e \u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cp\u003e \u003cb\u003eSynthesis of Au/Ag-NPs\u003c/b\u003e: The transmission electron microscopy (TEM) image shows the morphologies of the obtained materials (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). They are mainly spherical nanoparticles with uniform size, approximately 18\u0026thinsp;\u0026plusmn;\u0026thinsp;2 nm. The size distribution of the materials can be supported by the corresponding DLS spectrum, which exhibits a sharp peak at around 20 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). The high-resolution TEM (HRTEM) image displays clear and complete lattice fringes with a distance of about 0.23 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec), suggesting the good crystallinity of the nanoparticles. It can also be supported by the X-ray diffraction (XRD) pattern (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). There are four well-distinguishable diffraction peaks at 38.35, 44.57, 65.02 and 77.68 \u0026deg;, corresponding to the (111), (200), (220) and (311) planes of Au/Ag alloy, respectively (Card PDF#65-8424-Au-Ag). X-ray photoelectron spectroscopy (XPS) spectrum indicates that the obtained nanoparticles should be mainly composed of Ag and Au elements, as well as a certain amount of carbon and oxygen elements (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee). The atomic ratio of Ag to Au is about 5/3, which is consistent with the usage of raw materials. The high resolution XPS spectrum of Au\u003csub\u003e4f\u003c/sub\u003e shows two typical peaks of metallic Au at 83.08 and 86.78 eV (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ef), assigning to Au\u003csub\u003e4f7/2\u003c/sub\u003e and Au\u003csub\u003e4f5/2\u003c/sub\u003e, respectively [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The high resolution XPS spectrum of Ag\u003csub\u003e3d\u003c/sub\u003e exhibits two peaks of metallic Ag at 368.28 and 374.28 eV, attributed to the Ag\u003csub\u003e3d5/2\u003c/sub\u003e and Ag\u003csub\u003e3d3/2\u003c/sub\u003e, respectively [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The high resolution XPS spectrum of C\u003csub\u003e1s\u003c/sub\u003e presents the binding energy peaks of C-OH, C\u0026thinsp;=\u0026thinsp;O and COO\u003csup\u003e-\u003c/sup\u003e groups, suggesting the presence of carboxyl groups on the materials (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). The carboxyl groups can also be confirmed by the FTIR spectrum (Fig. S2). The results indicate that the obtained nanoparticles should be mainly composed of metallic Ag and Au, while the surface should be modified with a large number of carboxyl groups. The EDX mapping analysis shows uniform distribution of Ag and Au components in the nanoparticles (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eg). All the characterization results substantially demonstrate that the obtained spherical nanoparticles are Au/Ag-NPs. The Au/Ag-NPs are strongly negatively charged (Zeta potential: -18.8 mV) due to the surface-modified carboxyl groups, and show excellent dispersity in water (see the inset in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eh). The Au/Ag-NP sol displays a typical LSPR absorption band at around 445 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eh). The number is between the LSPR wavelengths of monodispersed AgNPs and AuNPs of similar size, which is also a typical feature of Au/Ag-NPs [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003ePreparation of Au/Ag hydrogel SERS chips\u003c/strong\u003e \u003cp\u003eTo prepare the hydrogel SERS chips, the obtained Au/Ag-NPs were dispersed in 10% PVA solution containing Ca\u003csup\u003e2+\u003c/sup\u003e ions of an appropriate concentration. The Au/Ag-NPs aggregate in the PVA solution due to interaction between the carboxyl groups on the Au/Ag-NPs and Ca\u003csup\u003e2+\u003c/sup\u003e ions [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. It can be seen that the yellow sol of Au/Ag-NPs turns to red as being added into the PVA solution (see the inset in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea), suggesting the formation of aggregated Au/Ag-NPs (a-Au/Ag-NPs). The formed a-Au/Ag-NPs exhibit good stability in PVA solution, and even after standing for several hours, there is no sign of precipitation. The a-Au/Ag-NPs produce a sharp LSPR peak at around 532 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea), which matches well with the commonly used laser wavelength of 532 nm in SERS detection. The TEM image indicates that the formed a-Au/Ag-NPs are mainly composed of dozens of Au/Ag-NPs (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). There are abundant nanogaps in the a-Au/Ag-NPs, which become electromagnetic \u0026ldquo;hot spots\u0026rdquo; under the irradiation of 532 nm laser. It should be pointed out that the LSPR peak of the a-Au/Ag-NPs is much sharper and stronger than that produced by the aggregated silver nanoparticles (a-AgNPs) obtained by the similar method [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. It should be related to the better size uniformity of the a-Au/Ag-NPs than the a-AgNPs. Whatever, the obtained a-Au/Ag-NPs should possess quite strong EM effect under the irradiation of 532 nm laser. After the physical crosslinking, Au/Ag hydrogel SERS chips are obtained (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec). It can be observed that the color of a-Au/Ag-NP in PVA solution remains almost unchanged during the physical crosslinking process, suggesting no significant change in the morphology of a-Au/Ag-NPs. Thus, molecules on the obtained Au/Ag hydrogel SERS chips can gain strong EM effect. As long as the target molecule has an appropriate molecular energy level to allow it to undergo PICT with Au/Ag-NPs, strong CM effect can be also received. Therefore, it can be expected that the Au/Ag hydrogel SERS chips have excellent SERS activity to many molecules.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e4-MBA is chosen as a model molecule to demonstrate the SERS activity of the Au/Ag hydrogel SERS chips. The Fermi level of Au/Ag-NPs was measured to be ~-4.72 eV (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed), and HOMO and LUMO of 4-MBA are \u0026minus;\u0026thinsp;8.48 and \u0026minus;\u0026thinsp;3.21 eV, respectively [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee, under the irradiation of 532 nm laser (2.33 eV), PICT from the Fermi level of Au/Ag-NPs to LUMO of 4-MBA is allowed. As expected, the Au/Ag hydrogel SERS chips show excellent SERS activity to 4-MBA. The SERS signal of 4-MBA can be still well distinguished even at a quite concentration of 1\u0026times;10\u003csup\u003e\u0026ndash;12\u003c/sup\u003e mol/L (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef). The enhancement factor (EF) is as high as 1.11\u0026times;10\u003csup\u003e11\u003c/sup\u003e (see the detailed calculation in the SI). In addition to high SERS activity, the hydrogel SERS chips show outstanding reliability. First of all, the hydrogel SERS chips show excellent signal uniformity. SERS spectra of 4-MBA were collected randomly from 50 points of the chips (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eg). All the spectra are highly consistent. The relative standard deviation (RSD) based on the peak intensity at 1071 cm\u003csup\u003e-1\u003c/sup\u003e in the 50 spectra is as low as 3.5%. Secondly, the SERS activity of the Au/Ag hydrogel SERS chips show good long-term stability. The peak intensity of 4-MBA at 1537 cm\u003csup\u003e-1\u003c/sup\u003e on the chip remains above 94% after three-month storage in refrigerator (Fig. S3).\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSERS response to OPs\u003c/strong\u003e \u003cp\u003eThe experimental results mentioned above suggest that the obtained Au/Ag hydrogel SERS chips have excellent activity, uniformity and stability, and thereby should be an ideal SERS platform for quantitative detection. To further confirm the reliability, the SERS platform was applied for the detection of OPs. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea-d show the molecular energy levels of four common OPs, namely dimethoate, chlorpyrifos, methyl parathion, and triazophos, as well as the PICT processes between the OPs and Au/Ag-NPs under the irradiation of 532 nm laser. HOMO and LUMO of dimethoate are \u0026minus;\u0026thinsp;9.07 and \u0026minus;\u0026thinsp;0.84 eV, respectively [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Both of them are far from the Fermi level of Au/Ag-NPs, and the PICT cannot be activated by the 532 nm laser (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). Consequently, the CM effect induced by PICT cannot be obtained. What\u0026rsquo;s worse, the poor conjugation of the molecules leads to small Raman cross section\u003csup\u003e2\u003c/sup\u003e. As a result, even though the obtained Au/Ag hydrogel SERS chip provides rich and strong electromagnetic \u0026ldquo;hot spots\u0026rdquo;, dimethoate shows nearly no any distinguishable SERS signal even at a high concentration of 10 \u0026micro;g/mL (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). Chlorpyrifos and methyl parathion have similar conjugation units, suggesting similar EM effect from the substrate. However, their CM effects are different. HOMO and LUMO of chlorpyrifos are \u0026minus;\u0026thinsp;8.37 and \u0026minus;\u0026thinsp;3.01 eV, respectively [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. PICT from the Fermi level of Au/Ag-NPs to the LUMO can be activated by the laser, producing CM effect. However, the laser energy is much bigger than the energy interval. The mismatched laser energy may limit the PICT efficiency, and inhibit the CM effect (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). As a result, the SERS response of the hydrogel SERS chip to the molecule is not quite sensitive (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). HOMO and LUMO of methyl parathion are \u0026minus;\u0026thinsp;6.97 and \u0026minus;\u0026thinsp;2.40 eV, respectively [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. The 532 nm laser can well activate simultaneously the PICT process from the HOMO of molecule to the Fermi level of Au/Ag-NPs and that from the Fermi level of Au/Ag-NPs to LUMO of molecule (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee). Therefore, methyl parathion can also gain strong CM effect, and shows strong signal on the hydrogel SERS chip (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef). HOMO and LUMO of triazophos are calculated to ~-6.66 and \u0026minus;\u0026thinsp;1.42 eV, respectively (Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e, Fig. S4). Similar to the case of chlorpyrifos, the laser energy does not closely match the energy gap involved in the PICT process for triazophos, which should also limit its CM effect to some extent (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eg). However, triazophos possesses a larger conjugated structure compared to chlorpyrifos, enabling it to achieve a stronger EM enhancement. Consequently, the SERS signal of triazophos on the obtained Au/Ag hydrogel SERS chip is also significantly stronger than that of chlorpyrifos (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eh). As presented in the above experimental results, the constructed Au/Ag hydrogel SERS chips are sensitive only to the OPs, which have big Raman cross section and propriate molecular energy levels meeting the necessary for the PICT with the Au/Ag-NPs, but are insensitive to other OPs. That is to say, the SERS response of the developed Au/Ag hydrogel SERS chips to triazophos and methyl parathion can largely resist the interference of other OPs, which is quite important for the selective detection.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eDeveloping SERS sensor for triazophos and methyl parathion\u003c/strong\u003e \u003cp\u003eThe hydrogel SERS chips are sensitive to both triazophos and methyl parathion, and the measured SERS spectra of the two OPs are quite different. Thus, SERS sensors can be developed simultaneously for the detection of triazophos and methyl parathion. First of all, the effect of the solvent on the SERS response to the two OPs was investigated. Apparently, the solvent greatly affects not only the SERS spectra of the two OPs, but also the intensity of their main peaks (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, b). It may be because the solvent not only affects the efficiency of OPs molecules passing through the hydrogel pores, but also affects the interaction sites of OPs molecules on Au/Ag-NPs in the hydrogel. It can be seen that ethanol suits for both the two OPs, and would be applied in the following detection. Secondly, the soaking time will affect the enrichment of OP molecules in the Au/Ag hydrogel SERS chips, and should be optimized. It can be clearly observed that as the soaking time increases, the SERS intensity of the two OPs first increases and then tends to stabilize (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec, d). Both the strongest characteristic peaks of methyl parathion at 1345 cm\u003csup\u003e-1\u003c/sup\u003e and triazophos at 1595 cm\u003csup\u003e-1\u003c/sup\u003e increase sharply with the soaking time in the first 25 min, but increase slightly with further soaking time (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ee, f). For rapid detection technology, short response time and high sensitivity are equally important. Therefore, the soaking time for the detection of the two OPs is selected as 25 min.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eUnder the optimized experimental conditions mentioned above, the constructed Au/Ag hydrogel SERS chips exhibit ideal SERS response to the two OPs. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, b shows the SERS spectra of methyl parathion and triazophos at various concentrations, respectively. It can be clearly seen that the main characteristic SERS peaks of methyl parathion can still be distinguished even at an extremely low concentration of 0.01 ng/mL, and the SERS peaks of triazophos can also be recognized at a low concentration of 0.1 ng/mL. Apparently, the values are much lower than the maximum residue limits set internationally for the two OPs [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Actually, the sensitivities are better than those of most reported rapid detection methods for the two OPs (Table S2-S3). It can also be observed from the fiugres, the SERS signals of the two OPs increase gradually as the concentration increases. The intensity of the strongest characteristic peak of methyl parathion at 1345 cm\u003csup\u003e-1\u003c/sup\u003e shows a good linear relationship with the logarithm of its concentration over a wide range of 0.01 to 1000 ng/mL, (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec). Similarly, the peak intensity of triazophos at 1595 cm\u003csup\u003e-1\u003c/sup\u003e also shows a good semi-logarithmic relationship with the concentration from 0.1 to 1000 ng/mL (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed). The results suggest that the constructed Au/Ag hydrogel SERS chips can act as a sensitive SERS platform for the quantitative analysis of the two OPs.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eExcept for the high sensitivity, the unique structure of hydrogels should endow the hydrogel SERS chips excellent anti-interference ability. Therefore, it can be expected that the constructed Au/Ag hydrogel SERS chips should exhibit outstanding practicability in the application of real samples. To check it, four real samples including apple, grape, orange and tea are used. Although the samples exhibit some background signals, they do not present any characteristic peaks of methyl parathion or triazophos (Fig. S5). The concentrations of methyl parathion and triazophos in the samples should be lower than the detection limits of the SERS platform, and can be ignored. Therefore, all the samples were spiked with 1 and 10 ng/mL methyl parathion or triazophos. It can be seen that all the spiked samples produce well distinguishable SERS signals of methyl parathion or triazophos (Fig. S6, S7), and the background signals from the samples are greatly inhibited. The recoveries of methyl parathion in the samples are in the range of 77.58\u0026thinsp;~\u0026thinsp;109.50%, and those of triazophos are in the range of 78.17\u0026thinsp;~\u0026thinsp;103.31% (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The acceptable results substantially confirm the reliability of the SERS platform for the detection of methyl parathion and triazophos in real samples.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRecovery tests for methyl parathion and triazophos using the designed SERS sensor.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSamples\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eMethyl parathion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eTriazophos\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSpiked (ng/mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDetected (ng/mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRecovery (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSpiked (ng/mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eDetected (ng/mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eRecovery (%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eApple\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e92.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e94.43\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eGrape\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e77.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e78.17\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e86.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e85.13\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eOrange\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e89.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e103.31\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e101.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e84.98\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e88.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e91.76\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e109.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e89.94\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eAu/Ag-NPs with a uniform diameter distribution of 18\u0026thinsp;\u0026plusmn;\u0026thinsp;2 nm have been synthesized and applied to construct hydrogel SERS chips. The formed a-Au/Ag-NPs in the hydrogel on one hand provide lots of electromagnetic \u0026ldquo;hot spots\u0026rdquo; to produce strong EM effect, and on the other hand provide a moderate Fermi level at -4.72 eV for the PICT with many molecules to gain strong CM effect. Meanwhile, the construction of hydrogel substrates significantly enhanced the homogeneity and stability of a-Au/Ag-NPs. The constructed Au/Ag hydrogel SERS chips have been proved to be a sensitive and reliable sensing platform for the detection of methyl parathion and triazophos in fruit and tea samples and also quantitative analysis of molecules having appropriate molecular energy levels for the PICT with the Au/Ag-NPs.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRongjing Hu: Data curation, Investigation, Methodology, Validation, Visualization, Writing \u0026ndash; original draft.\u0026nbsp;Shilan Fu: Investigation, Methodology, Validation, Writing \u0026ndash; original draft.\u0026nbsp;Jingwen Zhang: Investigation, Methodology, Formal analysis.\u0026nbsp;Jiadan Zhang: Conceptualization, Data curation, Validation.\u0026nbsp;Fengfu Fu: Conceptualization, Funding acquisition, Project administration, Resources.\u0026nbsp;Zhenyu Lin:\u0026nbsp;Conceptualization, Funding acquisition, Project administration, Resources.\u0026nbsp;Yongqiang Dong:\u0026nbsp;Conceptualization, Funding acquisition, Project administration, Resources, Supervision, Writing \u0026ndash; review and editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was financially supported by the National Key R\u0026amp;D Program of China (2023YFF1105300), the National Natural Science Foundation of China (22276032), the Natural Science Foundation of Fujian Province (2023N0030, 2022Y0059, 2022J01537).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo datasets were generated or analysed during the current study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e The authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSupplementary Information\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eThe online version contains supplementary material available at https:// doi. org/\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData will be made available on request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eFleischmann M, Hendra PJ, McQuillan AJ (1974) Raman spectra of pyridine adsorbed at a silver electrode. Chem Phys Lett 26(2):163\u0026ndash;166. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0009-2614(74)85388-1\u003c/span\u003e\u003cspan address=\"10.1016/0009-2614(74)85388-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang X, Huang SC, Hu S et al (2020) Fundamental understanding and applications of plasmon-enhanced Raman spectroscopy. Nat Rev Phys 2(5):253\u0026ndash;271. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s42254-020-0171-y\u003c/span\u003e\u003cspan address=\"10.1038/s42254-020-0171-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBell SEJ, Charron G, Cort\u0026eacute;s E et al (2020) Towards reliable and quantitative surface-enhanced Raman scattering (SERS): from key parameters to good analytical practice. Angew Chem Int Ed 59(14):5454\u0026ndash;5462. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/anie.201908154\u003c/span\u003e\u003cspan address=\"10.1002/anie.201908154\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDai Q, Huang J, Qiu X et al (2025) A chiral sensing system based on a single Au nanowire: a general SERS strategy for identification of enantiomers and mechanism for chiral interaction. Anal Chem 97(6):3765\u0026ndash;3772. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acs.analchem.5c00036\u003c/span\u003e\u003cspan address=\"10.1021/acs.analchem.5c00036\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang XX, Wang HJ, Yang JL et al (2023) Direct S\u0026ndash;H evidence revealing the photo-electrocatalytic hydrogen evolution reaction mechanism on CdS using surface-enhanced Raman spectroscopy. J Phys Chem Lett 14(17):4026\u0026ndash;4032. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acs.jpclett.3c00701\u003c/span\u003e\u003cspan address=\"10.1021/acs.jpclett.3c00701\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin L, He H, Xue R et al (2023) Direct and quantitative assessments of near-infrared light attenuation and spectroscopic detection depth in biological tissues using surface-enhanced Raman scattering. Med-X 1(1):2\u0026ndash;17. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s44258-023-00010-2\u003c/span\u003e\u003cspan address=\"10.1007/s44258-023-00010-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSong L, Xue F, Li TM et al (2025) Differential diagnosis of urinary cancers by surface-enhanced Raman spectroscopy and machine learning. Anal Chem 97(1):11939\u0026ndash;11941. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acs.analchem.4c05287\u003c/span\u003e\u003cspan address=\"10.1021/acs.analchem.4c05287\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRycenga M, Cobley CM, Zeng J et al (2011) Controlling the synthesis and assembly of silver nanostructures for plasmonic applications. Chem Rev 111(6):3669\u0026ndash;3712. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/cr100275d\u003c/span\u003e\u003cspan address=\"10.1021/cr100275d\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang L, Su LZ, Yu Z et al (2022) Quantitative detection of creatinine in human serum by SERS with evaporation-induced optimal hotspots on Au nanocubes. ACS Appl Nano Mater 5(4):4841\u0026ndash;4847. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acsanm.1c04421\u003c/span\u003e\u003cspan address=\"10.1021/acsanm.1c04421\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXu J, Xie LF, Zhu MJ et al (2024) Rapid sample pretreatment facilitating SERS detection of trace weak organic acids/bases in simple matrices. Anal Chem 96(15):5968\u0026ndash;5975. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acs.analchem.4c00229\u003c/span\u003e\u003cspan address=\"10.1021/acs.analchem.4c00229\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen M, Liu Z, Su B et al (2023) High-performance hydrogel SERS chips with tunable localized surface plasmon resonance for coordinated electromagnetic enhancement with chemical enhancement. Adv Opt Mater 11(7):2202852. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/adom.202202852\u003c/span\u003e\u003cspan address=\"10.1002/adom.202202852\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen M, Zhang J, Zhu X et al (2022) Hybridizing silver nanoparticles in hydrogel for high-performance flexible SERS chips. ACS Appl Mater Interfaces 14(22):26216\u0026ndash;26224. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acsami.2c04628\u003c/span\u003e\u003cspan address=\"10.1021/acsami.2c04628\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi G, Zhao X, Tang X et al (2024) Wearable hydrogel SERS chip utilizing plasmonic trimers for uric acid analysis in sweat. Nano Lett 24(42):13447\u0026ndash;13454. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acs.nanolett.4c04267\u003c/span\u003e\u003cspan address=\"10.1021/acs.nanolett.4c04267\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen Y, Zhang Z, Wu Y et al (2025) Utilizing hydrogel-isolated dual-carboxyl surface-enhanced Raman scattering probe for accurate online pH monitoring. ACS Sens 10(11):8975\u0026ndash;8982. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acssensors.5c03124\u003c/span\u003e\u003cspan address=\"10.1021/acssensors.5c03124\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXiao Z, Li Q, Liu H et al (2022) Adhesion mechanism and application progress of hydrogels. Eur Polym J 173:111277. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.eurpolymj.2022.111277\u003c/span\u003e\u003cspan address=\"10.1016/j.eurpolymj.2022.111277\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSerafinelli C, Fantoni A, Alegria ECBA et al (2022) Plasmonic metal nanoparticles hybridized with 2D nanomaterials for SERS detection: a review. Biosensors 12(4):225. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/bios12040225\u003c/span\u003e\u003cspan address=\"10.3390/bios12040225\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSong J, Nam W, Zhou W (2019) Scalable high-performance nanolaminated SERS substrates based on multistack vertically oriented plasmonic nanogaps. Adv Mater Technol 4(5):2202345. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/admt.201800689\u003c/span\u003e\u003cspan address=\"10.1002/admt.201800689\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFu X, Wu H, Liu Z et al (2024) MoS\u003csub\u003e2\u003c/sub\u003e nanosheets as substrates for SERS-based sensing. ACS Appl Nano Mater 7:3988\u0026ndash;3996. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acsanm.3c05606\u003c/span\u003e\u003cspan address=\"10.1021/acsanm.3c05606\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin J, Shang Y, Li X et al (2017) Ultrasensitive SERS detection by defect engineering on single Cu\u003csub\u003e2\u003c/sub\u003eO superstructure particle. Adv Mater 29(5):1604797. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/adma.201604797\u003c/span\u003e\u003cspan address=\"10.1002/adma.201604797\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXu W, Gong X, Xiao J et al (2012) Surface-enhanced Raman spectroscopy on flat graphene surface. Proc Natl Acad Sci USA 109(23):9281\u0026ndash;9286. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1073/pnas.1205478109\u003c/span\u003e\u003cspan address=\"10.1073/pnas.1205478109\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChaudhry I, Hu G, Ye H et al (2024) Toward modeling the complexity of the chemical mechanism in SERS. ACS Nano 18(32):20835\u0026ndash;20850. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acsnano.4c07198\u003c/span\u003e\u003cspan address=\"10.1021/acsnano.4c07198\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang P, Tanaka D, Ryuzaki S et al (2015) Silver nanoparticles with tunable work functions. Appl Phys Lett 107(15):151601. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1063/1.4933253\u003c/span\u003e\u003cspan address=\"10.1063/1.4933253\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMusa I, Ghabboun J (2025) Work function, electrostatic force microscopy, tunable photoluminescence of gold nanoparticles, and plasmonic interaction of gold nanoparticles/rhodamine 6G nanocomposite. Plasmonics 20:2531\u0026ndash;2540. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11468-024-02484-1\u003c/span\u003e\u003cspan address=\"10.1007/s11468-024-02484-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFang Y, Seong NH, Dlott DD (2008) Measurement of the distribution of site enhancements in surface-enhanced Raman scattering. Science 321(5887):388\u0026ndash;392. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1126/science.1159499\u003c/span\u003e\u003cspan address=\"10.1126/science.1159499\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLuo P, Li C, Shi G (2012) Synthesis of gold@carbon dots composite nanoparticles for surface enhanced Raman scattering. Phys Chem Chem Phys 14(20):7360\u0026ndash;7366. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1039/c2cp40767a\u003c/span\u003e\u003cspan address=\"10.1039/c2cp40767a\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang L, Jiang X, Ruan W et al (2009) Charge-transfer-induced surface-enhanced Raman scattering on Ag-TiO₂ nanocomposites. J Phys Chem C 113(36):16226\u0026ndash;16231. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/jp903600r\u003c/span\u003e\u003cspan address=\"10.1021/jp903600r\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQiu G, Ng SP, Wu CML (2018) Bimetallic Au-Ag alloy nanoislands for highly sensitive localized surface plasmon resonance biosensing. Sens Actuators B 265:459\u0026ndash;467. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.snb.2018.03.066\u003c/span\u003e\u003cspan address=\"10.1016/j.snb.2018.03.066\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen M, Su B, Wu H et al (2024) Hydrogel SERS chip with strong localized surface plasmon resonance for sensitive and rapid detection of T-2 toxin. Talanta 268:125329. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.talanta.2023.125329\u003c/span\u003e\u003cspan address=\"10.1016/j.talanta.2023.125329\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang N, Guo NS, Park E et al (2024) Surface plasmon resonance-induced charge transfer in Ag/mercaptobenzoic acid/polyaniline sandwich structures. J Phys Chem C 128(9):3876\u0026ndash;3884. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acs.jpcc.4c00292\u003c/span\u003e\u003cspan address=\"10.1021/acs.jpcc.4c00292\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSouza IC, Goncalves AS et al (2019) Computational studies of fullerene derivatives as pesticide captors. Orbital Electron J Chem 11(1):10\u0026ndash;17. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://dx.doi.org/10.17807/orbital.v11i1.1215\u003c/span\u003e\u003cspan address=\"10.17807/orbital.v11i1.1215\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSuresh I, Nesakumar N, Jegadeesan GB et al (2023) Quantification of chlorpyrifos residues in water under thermodynamically favorable electrodics using the f-MWCNT/N-(2-C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003eO)ED(CH\u003csub\u003e3\u003c/sub\u003eCOONa)\u003csub\u003e3\u003c/sub\u003e composite of superior selectivity. J Agric Food Chem 71(20):7642\u0026ndash;7653. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acs.jafc.3c00123\u003c/span\u003e\u003cspan address=\"10.1021/acs.jafc.3c00123\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHe K, Li Z, Wang L et al (2019) A water-stable luminescent metal\u0026ndash;organic framework for rapid and visible sensing of organophosphorus pesticides. ACS Appl Mater Interfaces 11(29):26250\u0026ndash;26260. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acsami.9b06151\u003c/span\u003e\u003cspan address=\"10.1021/acsami.9b06151\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang FW, Li YX, Ren FZ et al (2019) Toxicity, residue, degradation and detection methods of the insecticide triazophos. Environ Chem Lett 17:1769\u0026ndash;1785. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10311-019-00910-z\u003c/span\u003e\u003cspan address=\"10.1007/s10311-019-00910-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Au/Ag alloy, Localized surface plasmon resonance, Photo-induced charge transfer, Surface enhanced Raman scattering, Organophosphorus pesticides","lastPublishedDoi":"10.21203/rs.3.rs-9062681/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9062681/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA new method is developed to synthesize Au/Ag alloy nanoparticles (Au/Ag-NPs). The obtained Au/Ag-NPs are further dispersed in polyvinyl alcohol (PVA) solution to constructure Au/Ag hydrogel surface enhanced Raman scattering (SERS) chips through a simple Ca\u003csup\u003e2+\u003c/sup\u003e mediated aggregation of Au/Ag-NPs and a physical crosslinking of PVA. The formed aggregated Au/Ag-NPs (a-Au/Ag-NPs) show a strong localized surface plasmon resonance corresponding to the commonly used 532 nm laser. Therefore, under the action of 532 nm laser, the abundant nanogaps contained in the a-Au/Ag-NPs turn to high active electromagnetic \u0026ldquo;hot spots\u0026rdquo;, providing strong electromagnetic enhancement (EM). Moreover, Au/Ag-NPs provide a moderate Fermi level of -4.72 eV, which facilitates its photo induced charge transfer with many molecules under 532 nm laser, resulting in the chemical enhancement (CM) effect. The synergistic effect of EM and CM leads to ultrahigh SERS activity. Additionally, the unique structure of hydrogel provides excellent signal uniformity and robust anti-interference ability. Thus, the obtained Au/Ag hydrogel SERS chips are ideal SERS platform for the quantitative analysis of many molecules. For instance, a sensitive and reliable SERS method is established for the simultaneous detection of methyl parathion and triazophos in fruits and tea.\u003c/p\u003e","manuscriptTitle":"High hydrogel SERS platform based on Ag-Au alloy nanoparticles and its application for quantitative analysis of methyl parathion and triazophos","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-16 22:29:00","doi":"10.21203/rs.3.rs-9062681/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-15T09:44:49+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-11T12:26:07+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"288412860705945225041000455377227280425","date":"2026-03-30T03:00:44+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-20T13:31:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"321591922086320338688941824596795868277","date":"2026-03-15T15:53:07+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-13T15:34:46+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-10T15:55:03+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-10T00:33:38+00:00","index":"","fulltext":""},{"type":"submitted","content":"Microchimica Acta","date":"2026-03-08T07:49:40+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"5374372a-082c-4495-bee5-efd5a7990997","owner":[],"postedDate":"March 16th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-07T08:25:52+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-16 22:29:00","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9062681","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9062681","identity":"rs-9062681","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}